The indigo sources (at least the first two) seem more compelling to me, but at the same time, I prefer the violet colour as a bit more personable if I had to choose. What is the best bet, or are there other more reliable sources, and where is the difference coming from?

So the client has given you the PMS that they use for printed materials, and you are preparing onscreen materials to match?
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e100May 23 '11 at 15:42

for web. sorry, should have noted that. so i'm looking for an rgb conversion
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DamonMay 24 '11 at 11:39

Cough... <irony style="class: heavy;">Export them to jpeg/png and pick the one you prefer. If your site visitors all have monitors calibrated to match yours, then you'll have no problem.</irony>
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Alan GilbertsonMay 25 '11 at 1:10

the main issue is that from what i've found one is definitely purple and the other is definitely blue.. it's not a minor difference at all.
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DamonMay 26 '11 at 4:04

2

The current conversion specified by Pantone for HTML use is #280071. That is what you should use.
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Alan GilbertsonMay 26 '11 at 19:48

3 Answers
3

There is no such thing as a definitive conversion from a PMS colour to RGB, so if the client hasn't already determined what RGB value to use, and there isn't any previous web work to form a precedent, I'd recommend that you provide a few on-screen samples and get them to choose what they think is best by comparing with a Pantone swatch at their desks.

Explain that you are one person with a high end calibrated monitor, and so while you can provide a recommendation, it won't necessarily be the most suitable for the business-grade displays and lighting conditions their employees and clients will view the colour with.

Suggest that you could carry out testing on their premises if need be, but note that ultimately people do not actually compare print with screen, so a decision on a value in order to tie down consistency on the web s somewhat more important than exactly what that value is.

There is no substitute for an actual Pantone swatchbook if you are a) specifying color for a project and want to know accurately how it will print, or b) if you're putting together a color board for presentation to a client. There is no on-screen rendering that will show all PMS colors 100% accurately, or even some parts of the CMYK gamut -- the color gamuts don't completely overlap unless you're using one of the (extremely expensive) new Hewlett-Packard Dreamcolor monitors.

You will also see different renderings of PMS spot colors depending on which application you view them in. Photoshop uses the Lab values specified by Pantone, where Illustrator and InDesign, by default, render spot colors using Pantone's CMYK conversion values. Many a designer has been dismayed when placing a carefully crafted Photoshop image with spot colors, only to find the colors look different in InDesign than they did in Photoshop.

To make the displays match, you can tell Illustrator or InDesign to always display spots using Lab values, to make them consistent with Photoshop, or (preferably) you can turn on "Overprint Preview" in the View menu of either program.

I can't improve on Mordy Golding's excellent article on this subject here, which also covers how you can get the right values in the composite proofs you print locally.

Are you using the Pantone color as a reference to use it on the web or for print?
The only way to see colors accurately is to use a correctly calibrated monitor setup using the correct profiles in your software program. Even then it best it will be an approximation. One problem is that the Pantone system is subtractive and a monitor is additive, they have completely different ways to build the color and the gamut (range of colors) is also different.

In print: Ask for a proof at your printer. Consider also: will they be printed as Spot (one) color or CYMK-colors (built from 4 colors) as they will also look slightly different.

For web I mostly use these systems when a client want's a web page with a specific Pantone color. ....and then I play it by ear, because none of the website visitors have calibrated monitors (meaning I adjust the color by hand under a few lighting conditions and take an average value, this turns out fine usually) ;)